Racket is a ProgrammingLanguage (and implementation) descended from SchemeLanguage, including an IDE and a large number of built in libraries and tools. Racket also includes several secondary language dialects including R5RS, R6RS, lazy and typed variants, and teaching languages.

Performance-wise, Racket seems to currently (early 2011) be running only slightly slower (2-3x) than the statically typed languages like JavaLanguage and HaskellLanguage. This is according to the ComputerLanguageBenchmarksGame. This places it faster than any other dynamic language on the list.